Shot peening flow rate control

ABSTRACT

A shot peening flow rate control that is useful for non-ferrous shot peening media. The control has an inlet for receiving media and an orifice through which the media may pass that is in communication with the inlet. A valve selectively blocks the orifice. The valve has a spindle that is guided for axial movement between an open and closed position. The closed position blocks the orifice and the open position places the spindle spaced from the orifice to allow media to flow through the orifice. A flow sensor has a deflectable member that extends into a flow path of media leaving the orifice. In response to increasing or decreasing flow of the media through the flow path the deflectable member will deflect more or less. A sensing device measures the deflection in the deflectable member and generates an electrical signal that varies in response to deflection in the deflectable member.

BACKGROUND OF THE INVENTION

Treatment of a work piece by shot peening with granular media is animportant finishing step in an increasing number of products as thebenefits of doing so are becoming more well known. Controlling thepeening flow rate for dispensing the peening media is important toprovide predictable and repeatable results. In prior art peeningsystems, the flow rate of the media has been set with a fixed orificesometimes with a mechanical or electrical valve. However, feedback tothe controlling valve has not typically been provided by sensing theactual flow rate of media dispensed through the valve.

Often times the media used in peening is some type of ferrous metal.Spherically conditioned cut wire (SCCW) is often used due to its lowcost and the wire is a steel product. Controlling ferrous metals can bedone with a magnetic valve that when magnetized slows the fall of themetallic media through the valve. Sometimes, it is desirable to usenon-metallic media such as glass beads or other ceramic material. Inthis case, a magnetic valve will serve no purpose in metering flow.Ideally a valve for non-ferrous media should be able to control the flowrate based on measuring the flow rate dispensed by a valve and thenactuating the valve to achieve the desired flow rate.

SUMMARY OF THE INVENTION

The present invention is a shot peening flow rate control that has aninlet for receiving media and an orifice through which the media maypass that is in communication with the inlet. A valve selectively blocksthe orifice. The valve has a spindle that is guided for axial movementbetween an open and closed position. The closed position blocks theorifice, and in the open position the spindle is away from the orificeto allow media to flow through the orifice. The media leaving theorifice defines a flow path. A flow sensor has a deflectable member thatextends into the flow path. In response to increasing or decreasing theflow of the media through the flow path, the deflectable member willdeflect more or less. A sensing device measures the deflection in thedeflectable member and generates an electrical signal that varies inresponse to deflection in the deflectable member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overview of the shot peening control in a shot peeningsystem;

FIG. 2 is a view of the housing of the shot peening control open to showthe internal parts;

FIG. 3 is a sectional view taken about the line 3-3 in FIG. 2;

FIG. 4 is a view of the housing of the shot peening control open to showthe internal parts with the valve removed;

FIG. 5 is a sectional view taken about the line 5-5 in FIG. 4;

FIG. 6 is a view of the valve taken out of the housing;

FIG. 7 is a sectional view of the valve taken about line 7-7 in FIG. 6;and

FIG. 8 is a sectional view like that shown in FIG. 7 with the spindle inits open position.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows an overview of the shot peening flow rate control 6 of thepresent invention as it is incorporated in a shot peening system. As istypically done in shot peening, media 12 is held in a hopper 14 thatfeeds the shot peening system. The media 12 flows into an inlet 10 ofthe control 6 and out of an outlet 16 of the control 6. Once a properlymetered amount of media 12 having a desired flow rate leaves the outlet16, it is mixed with air from an air supply 18 that is directed into amixing tube 20 and leaves through a nozzle 24 that directs the mediaonto a work piece. Controlling the flow rate of air out of the airsupply 18 is relatively simple and well known in the art of peening.Controlling the rate of media 12 leaving the control 6 is necessary tohave a predictable mixture of air and media 12 that will be used to peenthe part. The more predictable the air/media mixture is, the morepredictable the peening results will be.

Controlling ferrous media may be done by taking advantage of itsmagnetic properties. However, when non-ferrous media such as glass orceramic is used controlling the media 12 is more difficult. The control6 of the present invention is adapted to handle non-ferrous media 12.The control 6 of the present invention has a housing 8 with its inlet 10connected downstream of the hopper 14. Immediately downstream of theinlet 10 is a valve chamber 28 that holds a valve 30. The valve 30 has avalve body 32 that is held with straps 34 in the valve chamber 28. Media12 can flow around all sides of the valve 30 as it passes through thevalve chamber 28.

The valve 30 includes a spindle 36 that has a rod 38 extending upwardlytherefrom as shown in FIG. 7. The rod 38 has a distal end 40 that isopposite the spindle 36. The rod 38 is magnetized and forms a firstpermanent magnet 42. The first permanent magnet 42 has a first pole 46that is within the spindle 36. In FIG. 7, the first pole 46 is the northmagnetic pole. The second pole 48 of the first permanent magnet 42 isupwardly facing in FIG. 7 and is the south magnetic pole. A spring 52 isplaced around the rod 38 and pushes down on the spindle 36. The rod 38and spindle 36 are guided for axial movement with respect to the valvebody 32. The rod 38 extends upwardly into bore 56 that extends upwardlyinto an electromagnet coil 60. The coil 60 has magnetic poles whenelectricity is passed through the coil 60. At a first end 62 the coil 60has a first pole 64; the first pole 64 is a south magnetic pole. At asecond end 66 the coil 60 has a second pole 68. The second pole 68 is anorth magnetic pole. At the end of the bore 56 is a second permanentmagnet 70. The second permanent magnet 70 is fixed with respect to thecoil 60 and has a first pole 74 and a second pole 76. The first pole 74of the second permanent magnet 70 is a north magnetic pole and facestoward the first permanent magnet 42. The spindle 36 has a conicalsurface 78 that is adapted for sealing against orifice 80. The valve 30will work if opposite poles of the first and second permanent magnets42, 70 face each other and the second pole 68 at the upper end of thecoil 60 is opposite the second pole 48 of the first permanent magnet 42.

The orifice 80 is located directly above a beam 84 that is a cantileverhaving free end 86 extending under orifice 80 and fixed end 88 that isheld in retention block 90. Media 12 flowing through the control 6 asshown in FIG. 1 defines a flow path 92. The flow path 92 leaving orifice80 strikes the beam 84 and bends it in proportion to the flow rate ofmedia contained within the flow path 92. A high flow rate of media 12would bend the beam 84 more than a low flow rate. The beam 84 is a flatpiece of resilient material such as thin metal that in the absence ofmedia 12 will return to a predetermined location and in response to aparticular flow rate be bent a predetermined distance downward. Beneaththe beam 84 is a proximity sensor 96 that returns an electrical signalproportional to the distance between the sensor 96 and the beam 84. Theproximity sensor is fixed to the housing 8. Because the proximity sensor96 detects the distance between itself and the beam 84, it measures thedeflection of the beam 84, thereby the proximity sensor 96 is used toindirectly measure the flow rate in the flow path 92. The media 12 afterstriking the beam 84 then leaves the housing 8 via outlet 16. The beam84 may be periodically changed by removing the retention block 90 andinstalling a new beam 84. This may be necessary over a long time of usedepending on the abrasiveness of the media 12.

It is desirable to have control over the flow rate in the flow path 92and this is achieved using the proximity sensor 96 in combination withthe valve 30. A predetermined rate that would be a good flow rate tohave in the flow path 92 is decided upon, and the control 6 iscalibrated to achieve that rate. A known quantity of media 12 may bedispensed through the control 6 over a prescribed amount of time andthis will yield a rate at which media 12 is being dispensed. This ratewill bend the beam 84 a certain amount and a sensor 96 reading may betaken and known to correspond with that rate. The signal from theproximity sensor 96 is used as an input to a controller circuit board102 that will send a predetermined amount of electricity to the coil 60.When the coil 60 has electricity passed through it, the first pole 64will be energized and the second pole 68 will also be energized. Asmentioned above, the first pole 64 is south and the second pole 68 isnorth. With the poles 64, 68 being energized, the first permanent magnet42 will be caused to move upward within the coil 60. As this happens,the spindle 36 moves upwardly and opens up the orifice 80, whichcorresponds to an open position of the spindle 36 as shown in FIG. 8.When there is no current passing through the coil 60, the spindle is inits closed position shown in FIG. 7. As the spindle 36 is moved fartherfrom the orifice 80, more media 12 will be allowed to flow through theorifice 80. The further the conical surface 78 of the spindle 36 is fromthe orifice 80, the higher the flow rate in the flow path 92 will be. Assuch the beam 84 will produce a proportional signal in the proximitysensor 96. This signal will be fed into the controller board 102 whichwill move the spindle up or down to adjust the flow rate to the desiredflow rate. As the spindle 36 moves upward, or more open, to affect ahigher flow rate, the spring 52 exerts a larger force. To assist inmovement upward of the spindle 36 the first permanent magnet 42 has itssecond pole 48 being opposite as the first pole 74 on the second magnet70. In other words, the opposite poles of the first and second magnets42, 70 face each other. Thus, an attractive force is generated betweenthe first and second 42, 70 permanent magnets that helps overcome theforce of the spring 52. This will result in less energy needed in thecoil 60 to move the spindle 36 upward. Typically, the electricitypassing through the coil 60 is done in pulses that keep the spindle 36at a particular location. Using different values in the algorithmcontrolling the flow rate, an operator can change the flow rate.

Upon leaving the outlet 16, the media 12 will be mixed with air from theair supply 18 and discharged through the nozzle 24. The media 12 leavingthe control 6 will be at a precisely measured flow rate. With the airfrom the air supply 18 set at a desired rate, the mixing ratio of air tomedia may be precisely determined to affect predictable peening.

The present invention is not limited to the details given above, but maybe modified within the scope of the following claims.

What is claimed is:
 1. A shot peening flow rate control comprising: aninlet for receiving media; an orifice through which said media may passin communication with said inlet; a valve for selectively blocking saidorifice, said media leaving said orifice defining a flow path; a flowsensor including a deflectable member extending into said flow path,said deflectable member being responsive to flow of said media in saidflow path to increase and decrease deflection of the deflectable memberin response to increasing or decreasing flow of said media through saidflow path; and a sensing device for measuring the deflection of saiddeflectable member and generating an electrical signal which varies inresponse to deflection in said deflectable member.
 2. The shot peeningflow rate control as claimed in claim 1, wherein said valve includes aspindle guided for axial movement between an open and closed position,said spindle contacting said orifice and blocking flow of said mediathrough said orifice in said closed position and said spindle beingspaced from said orifice in said open position thereby allowing flow ofmedia through said orifice.
 3. The shot peening flow rate control asclaimed in claim 2, wherein said spindle includes a spring urging saidspindle toward a closed position against said orifice, said spindleincluding a member extending toward an electromagnet so that whenelectricity passes through said electromagnet, said member is pulledtoward said electromagnet and away from said orifice.
 4. The shotpeening flow rate control as claimed in claim 3, wherein said memberincludes a first permanent magnet having opposite poles, a secondpermanent magnet is fixed with respect to said coil and having oppositepoles, said second permanent magnet being spaced from said firstpermanent magnet, said closed position of said spindle corresponding toa relatively farthest spacing between said first and second permanentmagnets, said open position of said spindle corresponding to arelatively closer spacing between said first and second permanentmagnets, opposite poles of said first and second magnets placed so thatsaid opposite poles face each other, attraction of opposite poles onsaid first and second magnets providing a force urging said spindle awayfrom said orifice.
 5. The shot peening flow rate control as claimed inclaim 4, wherein said member is a rod that is a first permanent magnethaving a distal end opposite said spindle, said electromagnet being acoil having a hollow center, a first pole being at a first end of saidcoil and a second pole at an opposite second end of said coil whenelectricity is passed through said coil, said rod extending inwardlyinto said center of said coil and said distal end of said rod beingnearer said first end of said coil when said spindle contacts saidorifice, said second permanent magnet being fixed adjacent to saidsecond end of said coil and having an opposite pole to said distal endof said rod facing said first permanent magnet, said second pole of saidcoil being a like pole to said pole of said second permanent magnet thatfaces said first permanent magnet.
 6. The shot peening flow rate controlas claimed in claim 5, wherein said deflectable member is a cantileveredbeam having a fixed end and a free end, said free end extending intosaid flow path.
 7. The shot peening flow rate control as claimed inclaim 6, wherein said sensing device is a proximity sensor fixed withrespect to said beam so that deflection of said beam changes spacingbetween said proximity sensor and said beam, said spacing being detectedby said proximity sensor.
 8. A shot peening flow rate controlcomprising: an inlet for receiving media; an orifice through which saidmedia may pass in communication with said inlet; a valve for selectivelyblocking said orifice, said valve including a spindle guided for axialmovement between an open and closed position, said spindle contactingsaid orifice and blocking flow of said media through said orifice insaid closed position and said spindle being spaced from said orifice insaid open position thereby allowing flow of media through said orifice,said media leaving said orifice defining a flow path; a flow sensorincluding a deflectable member extending into said flow path, saiddeflectable member being responsive to flow of said media in said flowpath to increase and decrease deflection of the deflectable member inresponse to increasing or decreasing flow of said media through saidflow path; and a sensing device for measuring the deflection of saiddeflectable member and generating an electrical signal which varies inresponse to deflection in said deflectable member.
 9. The shot peeningflow rate control as claimed in claim 8, wherein deflectable member is acantilevered beam having a fixed end and a free end, said free endextending into said flow path.
 10. The shot peening flow rate control asclaimed in claim 9, wherein said sensing device is a proximity sensorfixed with respect to said beam so that deflection of said beam changesspacing between said proximity sensor and said beam, said spacing beingdetected by said proximity sensor.
 11. The shot peening flow ratecontrol as claimed in claim 8, wherein said valve includes a springurging said spindle toward a closed position against said orifice, saidspindle including a rod extending toward an electromagnet so that whenelectricity passes through said electromagnet, said rod and said spindleare pulled away from said orifice.
 12. The shot peening flow ratecontrol as claimed in claim 11, wherein said rod is a first permanentmagnet, a second permanent magnet is fixed with respect to saidelectromagnet and having opposite poles, said second permanent magnetbeing spaced from said first permanent magnet, said closed position ofsaid spindle corresponding to a relatively farthest spacing between saidfirst and second permanent magnets, said open position of said spindlecorresponding to a relatively closer spacing between said first andsecond permanent magnets, opposite poles of said first and secondmagnets placed so that opposite poles face each other, attraction ofsaid opposite poles on said first and second permanent magnets providinga force urging said spindle away from said orifice.
 13. The shot peeningflow rate control as claimed in claim 12, said electromagnet being acoil having a hollow center a first pole at a first end of said coil anda second pole at an opposite second end of said coil when electricity ispassed through said coil, said rod extending inwardly into said centerof said coil and said distal end of said rod being nearer said first endof said coil when said spindle contacts said orifice, said secondpermanent magnet being fixed adjacent to said second end of said coil,said second pole of said coil being a like pole to said pole of saidsecond permanent magnet that faces said first permanent magnet.